Abstract
From ship hull response, viz, response amplitude operator and sea waves spectrum of ISSC, ship hull response in sea waves has been obtained, and the short term prediction method about ship propeller immersion has been derived.
Then, in the case where encounter conditions with several seaways are given, the long term prediction method has been offered.
The theoretical analysis results as to a 30, 000 gross tons bulk carrier with lower revolution larger diameter propellers have been shown.
(1) In the short term prediction calculation, the coming out probability of propeller blade tip over sea surface is the largest at a certain wave mean period.
Above the period the probability is larger at following sea sailing than at the case of head sea sailing.
In the case of head sea sailing, the probability at the case of lower speed sailing is smaller.
(2) In the long term prediction calculation according to Walden's observation data for the North Atlantic Ocean, the propeller tip coming out probability increases as propeller diameter increases. The probability becomes 18 times larger when propeller diameter increases by a factor of 1.5.
